64 C. WINKLEE. THE CENTRAL COUESE 



which crossing the raphe , seem to unite the two dorsal borders of 

 the two nuclei. (Plate IX fig. 15 N. 13 and Plate IX fig. 10 

 D in Ji). These fibres, also found in degeneration after removal of 

 the cochlea, may scarcely still be reckoned to the transversal fibres 

 of the corpus trapezoides. There will nevertheless exist a certain 

 arbitrariness in judging which of the transversal fibres may be recko- 

 ned still to the fibres of the corpus trapezoides, and which of them 

 deserve to be called ventral tegmental transverse fibres. In fact 

 the dorsal border of the corpus trapezoides is not precisely defined, 

 and therefore it is advantageous to reckon all transverse fibres in 

 the ventral part of the tegmenturn to the ,,systema ventrale nervi 

 octavi" and to use no longer the term of corpus trapezoides. 



In that case, the last-described root-fibres, which we will meet 

 again when discussing on the ,,systema intermedium nervi octavi" 

 and especially when their relation to the tracts of HELD and to 

 the auditory fibres of VON MONAKOW has to be settled, form the 

 utmost dorsal layer of the ,,systema ventrale nervi acustici". 



In this way MARcin-degeneration gives a special and very inte- 

 resting analysis of this system. As we have seen in the course of this 

 paragraph there are till now , demonstrated four portions in it. 



Firstly, there are root-fibres to the trapezoid-nuclei (stratum a 

 systematis ventralis). 



Secondly, there are root-fibres to the nuclei supra-olivaris (stratum 

 b systematis ventralis) and their surroundings. Both are degenerating 

 after the section of the n. octavus. 



Thirdly there are fibres , though partly mixed among the former 

 two, forming a third , still more dorsal layer in the systema ven- 

 tralis (stratum c systematis ventralis) not degenerating after the 

 section of the N. octavus and consequently no root/fibres. 



Fourthly , still more dorsally , a new small layer of rootfibres 

 appear (stratum ^systematis ventralis) , belonging only partially to the 

 systema ventrale, deriving for the greater portion their origin from 

 the intermedial octavus-system. Their significance will be discussed, 

 when treating of this latter. (Plate IX fig. 15 N. 13 and fig. 16 D). 

 They seem to unite the dorsal borders of the two nuclei olivares. 



f. The myelinisation-method offers the same results as tlie Marchi- 



method, as well in regard to the position of the transversal 



root-fibres in the systema ventrale nervi octavi, as to 



the position of the secundary fibres. 



The architecture of the systema ventrale N. octavi, as it has 

 been described in the precedent paragraph, is not such, as is 



